Film cut-out



H. E. BUTLER FILM CUT-OUT .March 25, 1930.

Filed NovA 5, 1928 MAGNET FEA.

Patented Mar. 25, 1930 UNITED STATE .AIENT oFLFIcE 'l HENRY E. BUTLER, EsooTIA, NEW YORK, AssIGNoR `rro `GENERAL EIEomRIo ooi/I PANY, AooRPoRA'I'IoNoE NEW YORK f FILM CUT- OUT 1 Application mea November 3,A192s.'Y serial' no. 317,023.

The present invention relates to circuit controllers of the type termedusually film cutouts and especially to film cutouts of the disk type.Film cutouts of the disk type are used extensively in connection withseries lighting circuits and the manner of their use is well-understoodby those familiar with such lighting circuits. The arrangement employedusually is well-illustrated in the patent to Howell, 717,201, datedDecember 30, 1902.

Disk film cutouts as heretofore made comprise two plates of thin metalbetween which is located a suitable insulating material, such as thinpaper, cloth, or the like, the plates and insulating material beingunited by an insulating adhesive such as shellac, for ergample.

In manufacturing film cutouts of this type, it is the practice to coatthe insulating maf terial with an adhesive and then place the coatedmaterial between the twoy plates, the adhesive serving to stick theparts together. With this arrangement, it has been found that there issometimes considerable variation in the dielectric strength of theinsulation, this being due to the fact that the coating may be appliedunevenly, or to the fact that in one instance the coating is thinnerthan in another instance. As a result in some cases the film willrupture at too low voltage while in other` cases, it will not ruptureuntil rthe voltage reaches an undesirably high value. A uniform productwhich will rupture always at the desired voltage is difficult toproduce.

The difliculties above lreferred to are.

especially noticeable in connection with the manufacture of disk filmcutouts for low voltage circuits, it being especially diicult to obtaina uniform product which will operate reliably on low voltage seriescircuits.

One object of my present invention is to provide an improvedco'nstruction of disk film cutout which will enablethe cutout to bemanufactured readily and at the same time provide cutouts having uniformbreakdown potentials.

A further object of my invention is to provide a disk type film cutoutwhich can be manufactured with accuracy for any desired breakdownvoltage, it being adapted to be made for low voltage circuits as wellrelatively high voltage circuits. I According to my invention, I rformmy improved disk film cutout from two metal pieces,-separated by a filmof insulatingmat'erial, but'instead of uniting the vparts 'byan adhesiveas heretofore, I altogether dispense with the use ofan adhesiveandinstead unite the two pieces magnetically; To this end,'IA form eitherone or both of the metal pieces from a material whichA is permanentlymagnetized. Preferably, I form only one of the v pieces of materialwhich is permanently magnetizedand form the other piece of any suitablemagnetic material. VAs' dielectric beV tweenthepieces I may employ asubstance such as lacquer, for example, sprayed onto one'orboth of thepieces or I may employ a separate material, suchas 'a thin sheetsubstance. f y

Inthe drawing, Fig. l is a vertical, sectional view ofa ldisk filmcutout embodyingmyi'nas for v vention ;Figl.2,is a perspective',exploded view of the parts which form the cutout'shown inA Fig. 1; Fig.3 is a sectional view of a modified formof disk film cutout, andF ig. 4'is van exploded perspective view of the parts forming the structureshown in Fig. 3. All the views are on `a greatly enlarged scale in orderto better illustrate A`the invention Referring tothe drawing, 1 and 2indicate the usual contact arms of a'series incandescent lamp receptaclesuch as is in common use'for incandescent" seriesv street lighting andIbe-l tween thev extremities of which the film cutouti's'located.

Referring to Figs. 1 'and 2, the two metal" pieces of theV film cutout,here shown as disks,

are kindicated at 3 and 4 and the material which forms the insulatingfilm between the pieces is indicated at 5. rlhe insulating film is shownas being in the form of a suitable coatingv on the member 4. Such acoating may be sprayed on and may comprise a suitable substance such asshellac, or the like. The member 3 is formed from suitable magneticmaterial, such as cold rolled steel. The member 4C is formed of magneticmaterial 'welhadapted to be magnetized and to'hold its magnetism.Preferably, I utilize a substance Y loe i such as cobalt steel for themember 4:. The member 3 is provided with a surrounding flange 6 withinwhich the member 4: is located, such flange serving to keep the membersfrom moving sidewise relatively to each other. The member 3 is thus inthe form of a shallow cup. When the members 3 and l are assembled withthe dielectric material between them, they are held in positionmagnetically, the magnetic Vattraction being sufliciently strong toprevent them from becoming separated. Y

In Figs. 3 and 4, is shown a modification of the invention wherein thedielectric is in the form of a thin sheet of dielectric material 7, heldbetween two disks 8 and 9, which corresponds to disks 3 and l of Figs. land 2. Material 7 may be thin paper, cloth or other suitable sheetmaterial By my invention, it will be seen that I am enabled to provide afilm cutout comprising only the two metal pieces and the dielectric filmbetween them. By this Yarrangement vI am enabled to select and provide adielectric film material which is uniform in dielectric strength andwhichwill puncture at the desired voltage value. As a result, I amena-bled toprovide film cntouts which will Mic in all cases be uniformin dielectric strength. This means that I am enabled to provide auniform product Vfor any desired voltage value.

by Letters Patent of the United States, is:

l. A film cutout comprising metal pieces separated by an insulatingfilm, said metal pieces being held together magnetically.

Y 2. A film cutout comprising metal pieces with an insulating filmbetween them, both of said pieces being formed from magnetic materialand at least one of said pieces being Y permanently magnetized.

3. A film cutout comprising a cupped metal piece, a second metal piecelocated in said cup, and dielectric material separating said pieces, atleast one of said pieces being permanently magnetized whereby said twopieces are held together magnetically.

`-In witness whereof, I have hereunto set my hand this 2nd day ofNovember, 1928.l

. HENRY E. BUTLER.

What I claim as new and desire to secureV

